Cocoa butter is dominated by three fatty acids, palmitic, stearic and oleic acid, and three triacylglycerols (TAGs) containing these particular fatty acids. Approximately 80% of the TAGs within cocoa butter are palmitate-oleate-palmitate (13–19%), palmitate-oleate-stearate (36–42%), and stearate-oleate-stearate (23–29%). Since cocoa butter is expensive, and its supply is limited, various alternatives have been proposed. Cocoa butter replacers are typically derived from partially hydrogenated, or partially hydrogenated and fractionated blends of soybean, canola, and palm oils. As such, these oils have a high amount of trans fatty acids. See, for example, Bailey's Industrial Oil& Food Products, Fifth Edition, John Wiley & Sons, Inc., Vol. 4, pp. 384–389 (1996).
Cocoa butter substitutes generally contain lauric acid as a main component (40–50%), and are typically derived from the oil and coconut palm. Genetic engineering has led to other plant sources having elevated levels of lauric acid. For example, U.S. Pat. No. 5,344,771 describes transgenic Brassica plants that produce canola oil that is rich in lauric acid.
Cocoa butter equivalents and extenders have a TAG composition that is similar to cocoa butter. Cocoa butter equivalents are derived from palm, illipe, shea, sal and kokum fats. Attempts to create other cocoa butter equivalents from oilseed plants have not been successful. For example, U.S., Pat. No. 5,723,595 describes transgenic Brassica plants that contain a delta-9 desaturase transgene. Oils extracted from these plants have increased amounts of stearic acid, but also contain increased amounts of linolenic acid and/or increased levels of long chain and very long chain fatty acids (18 carbons or greater).
Brassica plant lines with reduced levels of linolenic acid (2.5–5.8%) and elevated levels of oleic acid (73–79%) have been described (Pleines et al., Fat Sci. Technol., 90:167–171, 1988). Although there are certain problems associated with selecting mutant plants that have an altered content of linoleic and linolenic acids (Rakow et al., J. Amer. Oil Chem. Soc., 50:400–403, 1973), Stellar summer rapeseed oil that contains 3% linolenic acid and 28% linoleic acid has been reported (Can. J. Plant Sci., 68:509–511, 1988). In addition, a reconstituted line characterized by low linolenic and high linoleic content was produced by gene transfer in an interspecies cross from Brassica juncea into Brassica napus (Roy et al., Z. Pflanzenzuchtg, 95:201–209, 1985). Prospects for the development of Brassica napus having improved linolenic and linoleic acid content also have been reported (Roy et al., Plant Breeding, 98:89–96, 1987). Seeds and oils having 79% oleic acid and 3.5% α-linolenic acid also have been reported (European Patent application 323 751).